The subject matter of the present disclosure relates to lighting and lighting devices with particular discussion about a lamp with an omni-directional light source, a reflector, and a diffuser, wherein the lamp is configured to generate light at an optical intensity distribution substantially similar to the optical intensity distribution of common incandescent lamps.
Incandescent lamps (e.g., integral incandescent light bulbs and halogen light bulbs) mate with a lamp socket via a threaded base connector (i.e. an “Edison base” in the context of an incandescent light bulb), a bayonet-type base connector (i.e. bayonet base in the context of an incandescent light bulb), or other standard base connector. These incandescent lamps are often in the form of a unitary package that includes components to operate the lamps from a source of standard electrical power (e.g., 110 V and/or 220 V AC and/or 12 VDC and/or DC batteries). In the case of an incandescent lamp, the lamp comprises an incandescent filament operating at high temperature and radiating efficiently excess heat into the ambient. Moreover, the majority of incandescent lamps are naturally omni-directional light sources providing light with a substantially uniform optical intensity distribution (a “intensity distribution”).
Energy efficient lighting technologies include solid-state lighting devices such as LEDs, lamps having LEDs as a light source (LED lamp), and other LED-based devices often have performance that is superior to incandescent lamps. The superior performance of a solid-state lighting device can be quantified by its useful lifetime (e.g., its lumen maintenance and its reliability over time) and its higher efficacy as measured in Lumens per Electrical Watt (LPW)). For example, the lifetime of an incandescent lamp is typically in the range of approximately 1,000 to 5,000 hours as compared to the lifetime of LED-based lamps typically exceeding 25,000 hours. In another example, the efficacy of an incandescent lamp is typically in the range of 10 to 30 LPW as opposed to the efficacy of LED-based lamps being typically in the range of 40 to 100 LPW.
LED-based devices do have one disadvantage in some applications; namely, LED-based devices are highly unidirectional by nature. For example, common LED-based devices are flat and usually emit light from only one side of the device. Thus, although superior with respect to certain performance aspects, the intensity distribution of many commercially available LED lamps designed to be suitable alternative and/or replacement for incandescent lamps cannot replicate the intensity distribution of incandescent lamps in satisfactory manner or to a sufficient extent.
Another challenge related to solid-state lighting technologies is the need to find a way to dissipate heat adequately. For example, LED-based devices are highly sensitive to temperature variations with respect to the performance and reliability of the LED-based devices as compared to incandescent lamps containing incandescent or halogen filaments. This temperature sensitivity challenge is often addressed by placing a heat sink in contact with or in thermal contact with the LED-based device. Unfortunately, the heat sink, depending on the placement thereof, may block all or a portion of the light that the LED lamp emits, thus, may limit further the ability of the LED lamp to generate light with a more uniform optical intensity distribution. Moreover, physical constraints on lamps such as regulatory limits that define maximum dimensions for all lamp components, including light sources, limit further an ability to dissipate heat sufficiently and efficiently for LED-based lamps